Back-up power system for a cooling system
Patent 7566989 Issued on July 28, 2009. Estimated Expiration Date: 
December 13, 2025. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
December 13, 2025. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2958482 3336162 Redundant power supply system Vehicle having a fuel cell or battery energy supply network Multimode power processor Arrangement for ensuring uninterrupted current supply to an electrical consumer Uninterruptible power supply Off-board station and an electricity exchanging system suitable for use with a mobile vehicle power system Grid-linked power supply Fuel cell with proton conducting membrane InventorsAssigneeApplicationNo. 11302303 filed on 12/13/2005US Classes:307/64Substitute or emergency sourceExaminersPrimary: Paladini, Albert W.Assistant: Amaya, Carlos Foreign Patent References
International ClassesH02J 7/00H02J 9/00 DescriptionCROSS-REFERENCE TO RELATED APPLICATIONSNone. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT None. FIELD OF THE INVENTION In general, this invention is a back-up power supply system. More specifically, this invention relates to the field of providing back-up power for a cooling system for telecommunications and data center equipment. BACKGROUND OF THE INVENTION Traditionally, commercial power from a utility has been used as the primary source of electrical power for a consuming entity, such as a telecommunications facility. Within such a facility is a wide variety of computing equipment such asswitches, servers, routers, and other such devices. These devices, when in use, generate heat. This heat must be dissipated in order to avoid damage and possible malfunction of the computing equipment. As telecommunications equipment has advanced toinclude substantial amounts of digital equipment, maintaining sufficient climate control has become a greater concern to telecommunication providers, such that disruptions in telecommunication services caused by overheating are minimized. The most common climate controlling approach utilized in the past has been to cool an entire telecommunications facility with an air conditioning system. Typically, this air conditioning system is powered by an existing alternating current (AC)power source, primarily AC drawn from a utility company. A schematic diagram showing a typical prior art arrangement is shown in FIG. 1. Referring to the figure, an ordinary prior art system 110 includes an enclosed area, e.g., an entire facility, a room, or group of rooms, which includes a pluralityof pieces of equipment 116 which are computing devices that generate heat. AC power is administered through an AC bus 132. To cool these devices and other equipment within a telecommunications facility, a building air conditioner 118 is provided thatconsumes AC from AC bus 132. Because the computing equipment 116 consumes DC, the AC must be converted to DC using a rectifier 130. The primary source of power to the system is received into bus 132 from an AC utility 114 from outside the facility. Also outside of the facility is a diesel generator 120 which is only active if the AC utility 114 has failed, e.g., in a blackout, or where a power line has been taken out of service. The third and final backup source is a plurality of valve-regulatedlead-acid (VRLA) batteries 122 which are included in the DC circuit into which the equipment 116 is incorporated. The VRLA batteries must be stored inside the facility 112 because they cannot endure extreme temperatures. This AC dependent prior art system has proved disadvantageous in the event both the utility and diesel generator sources of AC are unavailable. The VRLA batteries 122 may provide backup for a limited time, but the facilities air conditioningsystem cannot draw power from them because it runs on AC. Further, the DC power available from the VRLAs 122 cannot be inverted to power the air conditioning system because the load requirements of the air conditioner are too great. Prior back-up power systems have been provided for telecommunications wherein only a portion of the back-up power is available for cooling the telecommunications and data devices. In such an arrangement, often times not all devices that requirecooling can be cooled, since back-up power is also required for other facility operations. These issues have caused operators to simply go without air conditioning and hope for the utility or diesel generator to come back on line before the temperature inside the facility reaches a level where the telecommunications and data equipmentsuffers heat-related damage. After that, if the AC sources are too late, the operator must decide whether to shut down, or endure equipment operational problems. SUMMARY OF THE INVENTION The present invention provides a power system that serves as a source of dedicated back-up power for a cooling system. The power system utilizes a plurality of fuel cells, which produce direct current (DC) power. A conversion device (e.g. aninverter) is necessary to convert the DC into alternating current (AC) for the cooling system. Presently cooling systems for such facilities, such as an air conditioner, operate on AC power. A transfer switch connects the AC power from the inverter tothe cooling system. The position of the transfer switch determines the source of AC power for the cooling system. In an embodiment of the present invention, the dedicated back-up power source comprises a source of DC, an inverter coupled to the source of DC, and a transfer switch capable of switching between a primary power source, such as a utility AC, andthe back-up power source. An associated method is directed towards providing a back-up power source for a cooling system and determining availability of power sources and air temperature levels proximate the telecommunications devices. In another embodiment, a telecommunications site for transmitting communications signals having a dedicated back-up power source for a cooling system is provided. The back-up power source comprises the source of DC, an inverter for convertingthe DC to AC, and a transfer switch, as previously discussed. BRIEF DESCRIPTION OF THE DRAWINGS The present invention is described in detail below with reference to the attached drawing figures, wherein: FIG. 1 is a schematic diagram showing a prior art power distribution backup and air conditioning systems used at a telecommunications facility. FIG. 2 is a schematic drawing showing a back-up power source and air conditioning system in accordance with an embodiment of the present invention. FIG. 3 is a flow diagram showing a method of providing a back-up power source in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention, a back-up power source for a cooling system for a data equipment facility having heat-generating equipment, such as a telecommunications facility, comprises a source of direct current (DC), an inverter to convert all of theDC to alternating (AC), and a transfer switch for directing the AC to the cooling system is shown in detail with (i) the schematic diagrams of FIGS. 1 and 2, and (ii) the flow chart of FIG. 3. Although the design concept is shown and discussed withrespect to telecommunications equipment, the invention is applicable to any type of heat-generating equipment present in a data center. Referring to FIG. 2, a dedicated back-up power source 200 for providing AC to a cooling system is shown in detail. Back-up power source 200 comprises a source of DC 202, which is preferably at least one fuel cell 204, and an inverter 206 that iscoupled to source of DC 202 for converting the DC to AC. The DC power generated by fuel cell 204 is provided to a DC bus 205 before passing through inverter 206. The resulting AC powers a cooling system 208, which for the embodiment shown in FIG. 2,comprises a plurality of air conditioners 220, 222, and 224. The back-up power source 200 also comprises a transfer switch 210 capable of switching between a primary power source 212 and back-up power source 200. In FIG. 2, transfer switch 210 ispositioned to couple primary power source 212 with cooling system 208. However, when back-up power source 200 is utilized, transfer switch 210 closes a circuit with source of DC 202 and inverter 206 such that all of the resulting AC power from inverter206 is directed to cooling system 208. Back-up power source 200 is activated when operating temperatures of predetermined telecommunications equipment exceed a predetermined limit and primary power source 212 is unavailable. One such example oftelecommunications equipment requiring cooling is a microprocessor-based telecommunications server or router, manufactured by a number of suppliers, such as Sun Microsystems, Hewlett-Packard, and Dell, to name a few, are designed to operate in conditionsunder 90 degrees Fahrenheit. Extended operation beyond these temperatures can result in performance problems and possible equipment failure. As previously mentioned, source of DC 202 is preferably a fuel cell 204. Furthermore, fuel cell 204 comprises at least one proton exchange membrane (PEM) 214. Fuel cell 204 is supplied with hydrogen from a plurality of tanks 216 that flowsthrough a conduit 218 before being directed into PEM 214. As one skilled in the art of fuel cell technology will understand, fuel cells are basically electrochemical energy conversion devices. That is, they utilize hydrogen and oxygen to createelectricity. Fuel cells have a proton exchange membrane (or other equivalent device) that temporarily remove the electron from hydrogen. Later this hydrogen electron is returned when the hydrogen is combined with oxygen. The reaction is non-combustiveand environmentally friendly with the only by products being heat and water, as DC electrical power is produced. Furthermore, as long as hydrogen is available to the fuel cell, DC power can be generated. The fuel cell is not like a battery thatdischarges over time. For the embodiment shown in FIG. 2, ninety-six tanks of hydrogen are provided. These tanks supply hydrogen to six 200A PEMs, with each PEM capable of producing 54V of DC. The DC from each PEM is supplied to DC bus 205, which, in turn is coupledto the inverter. Inverter 206, having 60 kVa output, produces the AC required to power the cooling system from the DC generated by the PEMs. Based on the quantity of equipment requiring cooling at a typical facility, this supply of stored hydrogen will yield up to 24 hours of cooling for the equipment. This time period of cooling can vary depending on the amount of hardware to coolas well as the amount of hydrogen available. Cooling time can be maximized by directing the cooling air to only the telecommunications devices that require cooling as opposed to the entire telecommunications facility. In the embodiment shown in FIG. 2,back-up power is supplied to the telecommunications devices from an alternate source such as a battery, such that no power from back-up power source 200 is required for purposes other than for operating a cooling system for the telecommunicationsdevices. Examples of the types of telecommunications devices that typically require cooling in order to operate within acceptable temperature ranges include, but are not limited to, routers, switching equipment, and other heat generating devices. An associated method is disclosed that is directed towards providing a back-up power source for a cooling system and determining the availability of the power sources and air temperature levels proximate the telecommunications devices. Thismethod is best understood with reference to the flow diagram shown in FIG. 3. In a step 300 the air temperature proximate the telecommunications equipment is monitored using an industry-standard equipment temperature sensor. In a step 302, adetermination is made regarding the availability of primary power source 212, which is typically a utility AC. If the primary power source is operational, then in a step 303, the position of switch 210 is verified to complete a circuit with the primarypower source 212. If the switch is not initially in this position, then it is moved to complete this circuit. A determination is made in a step 304 as to whether or not the air temperature proximate the telecommunications equipment exceedspredetermined limits. If the air temperature, as measured by the temperature sensor, is still within predetermined limits, then the process returns to step 300 to continue monitoring the air temperature. If the air temperature exceeds the predeterminedlimits, and the primary power source 212 is operational and connected to the cooling system through transfer switch 210, then it is understood that any issues regarding sufficient cooling of the telecommunications devices can be attributed to coolingsystem malfunctions, such as lack of coolant, frozen coils, blocked cooling ducts, etc. The cooling system is inspected and any necessary repairs are made in a step 306. If, in step 302, the determination is made that primary power source 212 is unavailable, then the determination is made at a step 308 if the air temperature proximate the telecommunications equipment exceeds predetermined limits. For themicroprocessor device previously discussed, the upper limit air temperature proximate the device is 90 deg. F. If the air temperature is acceptable and does not exceed this limit, then there is no need to provide cooling powered by the back-up powersystem to the telecommunications equipment at this time and the process again returns to step 300 for continual temperature monitoring and power source monitoring. If, however, the air temperature proximate the telecommunications equipment does exceedthe predetermined limits, then the back-up power source 200 is initiated in a step 310. Upon successful initiation of the back-up power source, proper positioning of transfer switch 210 is necessary to close a circuit between cooling system 208 and back-up power source 200. This repositioning, as necessary, occurs in a step 312. By default, since the preferred power source is the primary power generated by a utility, the initial position of transfer switch 210 completes a circuit with primary power source 212, as shown in FIG. 2. Once the circuit between cooling system 208 and back-up power source 200 is closed, power from the back-up source is directed to cooling system 208 in a step 314. In a step 316, a determination is made as to whether or not the air temperatureproximate the equipment is now below the predetermined limits. For the example device discussed herein, the air temperature proximate the microprocessor must be below 90 deg. F. If the air temperature has dropped to under these predetermined limits,such that the equipment has been properly cooled, then back-up power source 200 is shutdown in a step 318 and the process returns to step 300 for continual temperature monitoring and power source monitoring. Upon continual temperature monitoring, if the primary power source is still unavailable, and the air temperature limits are once again exceeded, the back-up power source is again initiated. However, as can be seen from steps 302 and 303 of FIG.3, transfer switch 210 is still connected to the back-up power source. Therefore, the transfer switch would not need to be repositioned to form a closed circuit with back-up power source 200 as previously defined in step 312. If the air temperature isstill above the upper temperature limits, then the process returns to step 314 where back-up source of DC continues to provide power to the cooling system for continual cooling of the telecommunications equipment. As previously mentioned, the back-up power source of DC is directed to supply power to a cooling system for telecommunications and data equipment. This arrangement is most commonly used at a telecommunications site that provides transmission ofcommunication signals across a network. A telecommunications site utilizes a primary AC power source for powering the telecommunications equipment as well as serving as the primary power source for the cooling system. While telecommunications sites areknown to have redundant back-up systems for powering the communications equipment, such as batteries and other energy storage devices, these back-up systems do not direct dedicated power to back-up the cooling system. The present invention provides aback-up power source comprising a source of DC, an inverter coupled to the source of DC for converting the DC to AC for powering the cooling system and a transfer switch capable of switching between a primary power source and the back-up power source. This arrangement is directed exclusively to the cooling system such that telecommunications equipment can be maintained within predetermined operating limits, even when operating on back-up power. It will be appreciated by people skilled in the art that the present invention is not limited to what has been particularly shown and described above. Rather, all matter shown in the accompanying drawings or described above is to be interpretedas illustrative and not limiting. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description. Other References
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